How to do a double window pane

First you look at your multiplication problem.

Then you draw a square and split it in four.

Then you split the numbers apart.

Then you place the numbers in the box.

You multiply 70x20 and 70x3.

Also multiply 20x7 and 3x7.

When you fill up the square you add up the numbers.

Then you get your answer 1,771.

The end.